This invention relates to heart valve prostheses for replacement of defective natural valves and more particularly to heart valve prostheses using a pivoting valve member.
Early designs of disc-shaped occluder heart valves, such as that described in U.S. Pat. No. 3,448,465, employ eccentric pivots by which the disc-shaped occluders pivot between an open position to allow blood flow through an annular passageway and a closed position in which blood flow through the passageway is blocked. In pivoting occluder heart valves, blood may tend to stagnate and clot around the pivots causing sticking of the valves. Furthermore, the continuous opening and closing of such a valve subject the pivots to continual wear which may limit the life of the heart valve.
In attempts to avoid potential problems associated with pivoting occluder valves, heart valves have been developed which have free-floating occluders. In U.S. Pat. No. 3,825,957, such an occluder has a central opening which follows a guide rod extending from the annular body of the valve, and in U.S. Pat. No. 3,835,475, a free-floating occluder is retained between upper and lower protrusions which extend from the annular body generally into the region of the passageway through the valve body. A limitation of such free-floating occluder heart valves is that the intrusions into the path of blood flow, which are necessary to retain the free-floating occluder, interfere with the smooth flow of blood through the valve.
The need continues for improved heart valve designs which will provide long-term trouble-free use, which respond quickly to pressure changes within the heart and which provide good blood flow by minimizing impediments in the blood flow path.
It is a primary object of the present invention to provide a pivoting occluder heart valve which has generally unobstructed blood flow, and which substantially eliminates problems due to pivot wear and blood stagnation at the pivots.